Circular  No   156. 


. 


tinted  States  Department  of  Agriculture, 

BUREAU   OF   ENTOMOLOGY 
L.  O.  HOWARD,   Entomologist  and  Clue!  oi  Bureau. 


[NSECT    DAMAGE   TO    MINE    PROPS    AND    METHODS    OF 
PREVENTING  THE  INJURY. 

f      1        S\ 

tigationa, 

i\  ntoDi  i  tion. 

the  principal  causes  of  the  deterio- 
ration  and   destruction   of  timb  !    in   mines.     The   injury    is 
ted  both  before  and  in  -  nl  in  the  mine. 
This  circular  is  based  on  special  investigations  in  cooperation  with 
mining  companies.     It  is  intended  to  give  preliminary  information 
on  the  principal  types  of  insect  injury   ind  to  show  bow  a  large  per- 
f  injury  can  be  prevented. 
In  recenl  publications    of  this  bun  rmation  is  given 
on  methods  for  the  prevention  of  injury  by  insects  t<  products, 
including  mine  props      S      ral  of  these  methods  have  been  adapted 
to  tlic  need  of  preventing  injury  i<>  this  special  class  of  product,  and 
are  included  in  the  present  circular. 

in.ii  i;v    i"   I  M'.\i:kid.  BOl  KD,    KKD  SPLIT   PBOF8   BZFOKE   r r  \<  i.mint   in 

MM'     MINI. 

Both  »ft  and  hardwood  timber,  which  has  been  Mid  for  mine 
props,  and  onbarked  props  thai  have  been  cut  and  left  lying  stacked 
in  the  woods  or  in  the  yard  at  the  entrance  to  the  mine,  are  liable  to 
infestation  with  the  grubs  or  larvae  of  wood-boring  insects.  These 
grubs,  which  hatch  from  eggs  deposited  by  winged  insects  attracted 
by  the  odor  of  the   fresh-cut   timber,  eontTm**i-la_\vorl\   in   the  props 


1  Insed  D«>pro.tnt!i>n<  in  North  American   For 
Dept     I  Insect  Injuries  to  Forest  Products.      ( 

Apr  .19 

•-Cir    166— 12 


V.    linrai, 


£PC 


2  INSECT   DAMAGE   TO   MINE   PBOPS. 

after  they  have  been  transported  from  the  woods  and  placed  in  the 
mine.  The  grubs  of  most  injurious  wood-boring  insects  can  not  be- 
come established  in  the  timber  unless  the  bark  is  on,  because  the  bark 
serves  as  a  protective  covering  under  which  the  eggs  can  be  deposited 
and  affords  proper  moisture  conditions  for  the  development  of  the 
young  grubs,  many  of  which  feed  on  the  inner  bark  before  entering 
the  wood.  The  principal  injuries  to  mine  props  by  wood-boring 
insects  are  those  caused  by  roundheaded  and  flatheaded  borers,  timber 
worms,  and  ambrosia  beetles. 

Injury  to  timbers  by  roundheaded  and  flatheaded  borers  and  tim- 
ber worms  consists  in  burrows  in  the  wood  made  by  grubs,  which 
hatch  from  eggs  laid  under  the  bark  by  winged  beetles.  These  bur- 
rows, often  of  large  size,  not  only  decrease  the  length  of  service  of 
the  timbers,  but  also  their  structural  strength.  Running  both  trans- 
versely and  longitudinally  through  the  wood,  these  holes,  even  if  the 
insects  have  discontinued  their  work,  afford  entrance  to  moisture  and 
wood-destroying  fungi ;  the  decay  is  thus  enabled  more  rapidly  and 
completely  to  penetrate  the  heartwood. 

Injury  by  ambrosia  beetles  consists  of  pinhole  and  bluing  defects 
in  the  wood.  The  pinhole  defects  also  contribute  to  more  rapid 
decay. 

There  is,  therefore,  a  complicated  interrelation  between  these  wood- 
boring  insects  and  wood-destroying  fungi  in  the  deterioration  of  mine 
timbers. 

INJURY  TO  PROPS  AFTER  PLACEMENT  IN  THE  MINE. 

In  the  Southern  States  the  principal  injury  to  props  and  other 
timbers  in  slope  or  incline  mines  is  caused  by  small,  white,  soft- 
bodied  insects  known  as  "  wood  lice,"  white  ants,  or  termites.  These 
destructive  insects  work  in  moist  or  decaying  wood.  Timbers  placed 
on  the  heavily  timbered  slope  or  incline,  extending  from  250  to  300 
feet  from  the  exterior  into  the  mine,  are  attacked  by  termites,  as 
are  those  used  in  "headings"  near  the  surface  of  the  ground.  Indi- 
viduals of  the  winged  form  enter  the  mine  and  establish  colonie-  at 
the  base  of  the  props.  The  moist  condition  of  the  prop  at  the  base, 
where  the  wood  is  in  contact  with  the  ground  and  where  there  is 
usually  incipient  decay,  offers  especially  favorable  conditions  for 
injury  by  this  class  of  insects. 

The  presence  of  these  insects  is  not  easily  detected.  Their  work 
is  hidden  beneath  an  outer  shell  of  wood,  often  very  thin,  but  always 
left  intact;  therefore  an  ordinary  inspection  of  the  exterior  of  the 
props  will  not  reveal  the  presence  of  the  insects  or  their  destructive 
work.  The  entire  interior  may  be  completely  honeycombed  while 
there  is  nothing  on  the  exterior  to  indicate  the  injury.  Sometimes 
an  earthy  matter — partially  digested  wood  mixed  with  earth — is  em- 

[Clr.  156] 


!.\-i  .   i    DAM  \'.i     I"    MINI     PB0P8.  •'{ 

ployed  in  cover  over  such  parts  of  their  work  as  would  otherwise  be 
exposed  to  1 1 1«-  light,  which  thej  carefully  ;i\<>i,|. 

Ii   is  well  known  thai   when  once  these   insects  have  gained  an 
entrance  to  the  outer  moist  <>r  decayed  layers  of  wood  they  can  con 
limn'  their  destructive  \\'>rk  into  the  90imd  heartwood;  on  ill 
count  it  is  \«'i\  important  t"  prevent  them  from  becoming  established. 

PREVENTIOM    OF     Mil     INJUR!      I"    DN  BARKED,    ROUND,     \\i>    BPU1     PROPS 
BJ  I  I  »RJ     PLACEMEN!    in     i  mi     MINE. 

I'.,  simply  adapting  methods  <>f  handling  the  timbers,  before 
placement,  t<>  well-known  facts  in  tin-  life  history  of  the  insects  .1 
large  percentage  of  injur]  can  be  prevented.  It'  a  sufficient  quantity 
of  props  be  cul  far  enough  ahead  of  the  time  when  needed,  and  stored 
either  in  the  \  ait  I  at  the  mine  or  in  ;i  general  storage  yard  most 
siblc  to  the  largest  number  of  mines,  they  can  Ik-  properly 
handled  to  prevent  insect  injury  and  ;i  reserve  supply  established. 
The  logs  should  be  barked  in  the  woods  wnlun  ;i  few  days  after 
felling  the  trees.  A.fter  cutting  ini<>  props  they  should  be  trans- 
ported to  the  place  of  storage  and  piled  in  loose  stacks  in  such  a 
manner  as  t<>  facilitate  rapid  drying,  guarding  against  excessive 
checking.  After  a  reserve  supply  has  l"'1!!  established  it  will  n<> 
longer  be  necessary  to  cut  mine  timber  during  the  warmer  months 
when  tlif  insects  which  deposit  eggs  in  the  bark  or  wood  are  flying. 
llif  periods  during  which  these  insects  are  flying  vary  with  the 
locality  and  the  species  of  insect,  l>ut.  in  general,  in  the  region  north 
tit"  the  Gulf  States  the  period  of  activity  is  from  April  to  the  middle 
>t'  October.  In  all  cases  where  timbers  are  to  be  left  stacked,  either 
in  the  woods  or  yard,  the  bark  must  be  removed  before  the  end  of 
M      h  to  a\ « » i « 1  attack  by  insects. 

l'»\  barking  and  seasoning  mine  timbers,  insect  injury  before  place- 
ment will  not  only  be  prevented,  but  injury  by  termites  after  place- 
ment will  also  be  delayed  or  under  some  conditions  even  prevented 
and  the  length  of  life  of  the  timbers  prolonged. 

Therefore  the  timber  should  always  be  barked  except  in  rare  in- 
stances  where  it  is  to  be  used  in  workings  of  a  very  temporary  char- 
acter. It'  unbarked  round  or  split  props  are  to  be  used  in  temporary 
workings  where  it  would  not  be  practicable  to  remove  the  I >ark.  the 
should  be  cut  during  the  fall  and  early  winter.  A-  soon  as 
possible  after  cutting,  prop-  should  be  stacked  in  "open-crib"  pile3 
in  a  place  where  they  will  dry  most  rapidly,  without  excessive  check- 
ing, preferably  after  they  have  been  transported  from  the  woods,  be- 
cause  if  the  inner  bark  i>  dried  <>ut  before  the  insects  begin  to  fly  in 
the  spring  the  more  destructive  insects  will  n<>i  attack  them.  >plit 
prop-  should  be  piled  with  the  hark  side  up  so  thai  the  inner  bark 
will  dry.    I.,  gs  or  prop-  should  not  be  left  lying  on  the  ground.    I  n- 

[Olr.  166] 


1NSKCT    DAMAGE    TO    MIL,*, 


UNIVERSITY  OF  FLORIDA 

Nlllllllllllllllllllillllllllllllll 

3  1262  09216  6106 


harked  props,  especially  props  cut  from  insect-killed,  fire-killed,  or 
other  dead  standing  timber,  .should  be  thoroughly  inspected  before 
they  arc  placed  in  the  mine  and  all  props  showing  serious  damage  l>v 
insects  discarded.  The  presence  of  wood-boring  insects  can  be  de- 
tected by  sawdust-like  boring  dust  thai  is  expelled  from  their  bur- 
rows and  lodges  in  crevice.-  in  the  hark. 

PREVENTION    OF    INJTJRT    TO    TIMBERS    BY    TERMITES    Al'JT.i;    PLACEMENT. 

As  previously  stated,  the  seasoning  that  prevents  injury  before 
placement  will  delay  and  under  some  conditions  even  prevent  injury 
to  mine  timbers  hv  termites  after  placement,  since  moisture  or  incip- 
ient decay  is  necessary  for  destructive  work.  In  consequence, 
soiling  is  recommended  where  it  is  impracticable  to  treat  timbers 
with  chemical  preservatives. 

Methods  of  superficially  treating  props  by  brushing  the  exterior 
with  various  chemical  preservatives  will  be  temporarily  effective  in 
keeping  out  termites,  if  the  work  is  thoroughly  done  and  both  ends 
are  also  treated.  Where  the  basal  area  is  left  untreated,  termite- 
will  enter  the  prop  through  the  untreated  portion.  It  will  readily 
be  seen  that  neither  brushing  nor  spraying  the  exterior  of  the  prop 
after  placement  in  the  mine,  as  is  sometimes  practiced,  is  effective 
in  keeping  out  termites,  since  the  end  that  sets  in  the  ground  could 
not  be  treated,  and  it  is  usually  here  that  termite.-  attack  the  props. 

Before  treating  timber  with  chemical  preservatives, especially  where 
the  brush  method  is  used,  it  is  essential  that  the  timber  be  thoroughly 
seasoned,  otherwise  penetration  will  he  retarded. 

Impregnating  props  intended  for  permanent  service  with  creosote 
by  some  standard  process  (either  by  the  "open-tank"  or  by  the 
cylinder-pre»ure  processes)  will  keep  out  termites  and  other  wood- 
boring  insects  and  preserve  the  prop-  for  a  much  longer  period  than 
they  would  last  untreated. 

Publications  of  the  Forest  Service  should  he  consulted  for  infor- 
mation on  general  methods  of  treating  timbers  with  preservatives 
and  the  relative  efficiency  of  various  methods  and  chemicals.1 

Approved: 

James  "Wilson, 
Secrt  tary  of  Agriculture. 
Washington,  D.  C,  April  JO.  1912. 

1  See  especially  Bulletin   107  of  the   Forest   Service,   D.   S.   Department  of  Agriculture, 
"  The  V reservation  of  Mine  Timbers." 
U'ir.  156] 


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